Monday, March 3, 2014

I Can See Your Connectome From Here...

Differences in the Brain - Are men or women really superior to each other at certain tasks?
Nicole Uibel

The difference between men and women’s behavior has been a hot topic for centuries. Personal explanations for why the opposite sex thinks and behaves as they do generally takes on a turn like this:

In this image, we can see some generalizations about each sex. Women clearly love chocolate and have 'mystery moods,' while men's brains are dominated by sex. Or something like this, where society has simplified the man's brain to simple switch, while modeling a woman as complicated.

With the fight for equality between the sexes so publicized and hotly debated, the notion that our brains may actually be different comes as almost an insulting notion. Debated in forums ranging from suffrage to Cosmopolitan magazine, women in particular have fought for cultural acceptance that we are in effect "the same."
Despite the fights and claims, for decades we have been attempting to decipher the behavior of the opposite sex through magazine articles and books such as “Men are from Mars, Women are from Venus.” We constantly complain about the behavior of the opposite sex, exasperated about why we don't understand each other. We are at a crossroads of claiming equality while blaming behavior on other factors. Perhaps instead of looking into these media for answers, we should look to neuroscience.

Now, before we get too uncomfortable with the implications of this research, let’s step back and appreciate the other sex for all of the wonderful ways we complement each other. Now let’s tear down those complements and look at just how different we are.

One touchy subject area has been the finding that men have larger relative brain size than women do. For years, popular science avoided this subject by claiming men’s brains were larger because men are larger. However, studies have found that on average, men do have larger brain size corrected for body size compared to women, by almost 100 grams. Now if you’re a female, you probably have the same reaction I did when I read this:
I mostly had this reaction because of research which has supported the hypothesis that larger brains are correlated to increased intelligence. Researches found correlations between brain size and increased IQ's, but did not account for sex. Now, before all the males reading this swell their brains anymore with theories of superiority, read on.
Fear not ladies, we have those men beat in a few ways. For one, women’s brains have been shown to contain more white matter, which we know helps to connect neurons together. One study found that women’s brains may contain up to ten times more white matter compared to a man’s brain. All these extra connections mean ladies brains are a bit more complicated in set up, but more connections leads to increase workflow. This evidence, along with new research that suggests women have more neurons compared to men (as much as 12% more), is one reason women’s brains may work faster than men’s. 

However, we can also see in this image that men's brains contain more gray matter than women's brains. Gray matter, which represents the information processing centers of the brain, is shown to be as much as six and half times greater in men's brains. This increased gray matter may result in more information being processed, but the decreased area of white matter means that information will take longer to be processed. 

So are we even? Big brain with more gray matter for increased neurons and more white matter? If only it was so easy.

Recent research has been making huge advancements in brain mapping. One technique, diffusion tensor imaging (DTI), has given us some brilliant insight into the difference between men and women’s brains. Dr. Verma of University of Pennsylvania in Pittsburgh mapped out brain connections in roughly 950 subjects. What he found is incredible.

The map-like outcome of this study displaying different neural pathways in the brain was termed ‘connectome.’ What we are looking at, is essentially all of the connections between different parts of our brains. This map is a product of tracing and highlighting the fiber pathways linking different regions of the brain. Interestingly, Dr. Verma noted that these differences are only discernible after puberty.

We can see that the male brain depicted above has more connections laterally, in the same hemisphere. Comparatively, the female brain has more connections spanning the hemispheres, crossing back and forth between the right and left. Some of the extrapolations made from this research include rationales for why men are better at spatial tasks, such as map reading, while women are better at language and memory tasks, like recalling conversations. 

There is clearly much more research to be done in this field - and an interesting crossover study between neuroscience and psychology could be in order to examine the brain to behavior connection with many of the tasks listed here.

For more information on the 'connectome' project, check out this website

Ankney, C. D. 1992. Sex differences in relative brain size: the mis-measure of women too? Intelligence 16:329-336.

Connor, S. 2013. The hardwired difference between male and female brains could explain why men are better at map reading. The Independent. 

Edmunds, M. 2008. Do men and women have different brains? 

Ingalhalikar, M., A. Smith, D. Parker, T. D. Satterthwaite, M. A. Elliott, K. Ruparel, H. Hakonarson, R. E. Gur, R. C. Gur, and R. Verma. 2014. Sex differences in the structural connectome of the human brain. PNAS 111:823-829.

Kimura, D. 1987. Are men’s and women’s brains really different? Canadian Psychology 28:133-147.

University of California, Irvine. 2005. Intelligence in men and women is a gray and white matter. ScienceDaily. 

Willerman, L. and R. Schultz. 1991. In vivo brain size and intelligence. Intelligence 15:223-228.

1 comment:

  1. Really interesting blog Nicole! Keep up the fun, intelligential posts!